🐇 Elixir RabbitMQ Client

rabbit_mq is an opinionated RabbitMQ client to help you build balanced and consistent Consumers and Producers.

Table of contents

• Installation and Usage
• Documentation
• Configuration
• Balanced performance and reliability
• Consistency
• TODO

Installation and Usage

Add :rabbit_mq as a dependency to your project's mix.exs:

defp deps do
  [
    {:rabbit_mq, "~> 0.0.0-alpha-8"}
  ]
end

Documentation

The full documentation is published on hex.

The following modules are provided;

• RabbitMQ.Topology
• RabbitMQ.Consumer
• RabbitMQ.Producer

Configuration

The following can be configured.

config :rabbit_mq,
  amqp_url: "amqp://guest:guest@localhost:5672",
  heartbeat_interval_sec: 60,
  reconnect_interval_ms: 2500,
  max_channels_per_connection: 16

• amqp_url; required, the broker URL.
• heartbeat_interval_sec; defines after what period of time the peer TCP connection should be considered unreachable. Defaults to 30.
• reconnect_interval_ms; the interval before another attempt to re-connect to the broker should occur. Defaults to 2500.
• max_channels_per_connection; maximum number of channels per connection. Also determines the maximum number of workers per Producer/Consumer module. Defaults to 8.

⚠️ Please consult the Channels Resource Usage guide to understand how to best configure :max_channels_per_connection.

⚠️ Please consult the Detecting Dead TCP Connections with Heartbeats and TCP Keepalives guide to understand how to best configure :heartbeat_interval_sec.

Balanced performance and reliability

The RabbitMQ modules are pre-configured with sensible defaults and follow design principles that improve and delicately balance both performance and reliability.

This has been possible through

• a) extensive experience of working with Elixir and RabbitMQ in production; and
• b) meticulous consultation of the below (and more) documents and guides.

⚠️ While most of the heavy-lifting is provided by the library itself, reading through the documents below before running any application in production is thoroughly recommended.

• Connections
• Channels
• Reliability Guide
• Publisher Confirms
• Consumer Acknowledgements and Publisher Confirms
• Consumer Acknowledgement Modes and Data Safety Considerations
• Consumer Prefetch
• Production Checklist
• RabbitMQ Best Practices
• RabbitMQ Best Practice for High Performance (High Throughput)

Consistency

The RabbitMQ modules are designed to help you build consistent, SDK-like Consumers and Producers.

defmodule CustomerProducer do
  use RabbitMQ.Producer, exchange: "customer"

  @doc """
  Publishes an event routed via "customer.created".
  """
  def customer_created(customer_id) do
    opts = [
      content_type: "application/json",
      correlation_id: UUID.uuid4(),
      mandatory: true
    ]

    payload = Jason.encode!(%{version: "1.0.0", customer_id: customer_id})

    publish(payload, "customer.created", opts)
  end

  @doc """
  Publishes an event routed via "customer.created".
  """
  def customer_updated(customer_data) do
    opts = [
      content_type: "application/json",
      correlation_id: UUID.uuid4(),
      mandatory: true
    ]

    payload = Jason.encode!(%{version: "1.0.0", customer_data: customer_data})

    publish(payload, "customer.created", opts)
  end
end

TODO

A quick and dirty tech-debt tracker, used in conjunction with Issues.

• [ ] Add support for notifying the parent producer when a publisher nack occurs.